Semiconductor device and method for manufacturing the same

Abstract

A semiconductor device is provided that has MIS transistors with metal gates that can prevent an increase in the number of manufacturing steps as much as possible and also restrain difficulties in the manufacturing conditions. This semiconductor device has a substrate; and an n-channel MIS transistor including: a p-type semiconductor layer formed on the substrate; a pair of n-type source/drain regions formed in the p-type semiconductor layer and isolated each other; a first gate insulating film formed on the p-type semiconductor layer and located between the pair of n-type source/drain regions; and a first gate electrode formed on the first gate insulating film and containing an alloy of a rare-earth metal and a metal selected from the group consisting of Ru, Pt, and Rh.

1 . A semiconductor device comprising 
 a substrate; and    an n-channel MIS transistor including: 
 a p-type semiconductor layer formed on the substrate;  
 a pair of n-type source/drain regions formed in the p-type semiconductor layer and isolated from each other;  
 a first gate insulating film formed on the p-type semiconductor layer and located between the pair of n-type source/drain regions; and  
 a first gate electrode formed on the first gate insulating film and containing an alloy of a rare-earth metal and a metal selected from the group consisting of Ru, Pt, and Rh.  
   
   
   
       2 . The semiconductor device according to  claim 1 , wherein the n-channel MIS transistor has a first tungsten layer provided between the first gate insulating film and the first gate electrode.  
   
   
       3 . The semiconductor device according to  claim 1 , wherein a ratio of the composition concentration (atomic %) of the rare-earth metal to the selected metal is in the range of 2.5 to 3.  
   
   
       4 . The semiconductor device according to  claim 1 , wherein a region in which a ratio of the composition concentration (atomic %) of the rare-earth metal to the selected metal is in the range of 2.5 to 3 is located at a portion of the first gate electrode on the side of the first gate insulating film, and has a film thickness of 1.5 nm or larger.  
   
   
       5 . The semiconductor device according to  claim 1 , wherein the rare-earth metal is one of Er, Y, La, Gd, and Yb.  
   
   
       6 . The semiconductor device according to  claim 1 , wherein the alloy of the selected metal and the rare-earth metal is RuEr 3  alloy.  
   
   
       7 . The semiconductor device according to  claim 1 , wherein an insulating film of the same material as the first gate insulating film is formed on side faces of the first gate electrode.  
   
   
       8 . The semiconductor device according to  claim 1 , wherein the first gate insulating film is one of SiO x N y , HfO 2 , HfO x N y , HfSi x O y , HfSi x O y N z , HfAl x O y , HfAl x O y N z , LaHf x O y , LaAl x O y , Al 2 O 3 , ZrO 2 , ZrSi x O y , and ZrSi x O y N z .  
   
   
       9 . A semiconductor device comprising: 
 a substrate;    an n-channel MIS transistor including: a p-type semiconductor layer formed on the substrate; a pair of n-type source/drain regions formed in the p-type semiconductor layer and isolated from each other; a first gate insulating film formed on the p-type semiconductor layer and located between the pair of n-type source/drain regions; and a first gate electrode formed on the first gate insulating film and containing an alloy of a rare-earth metal and a metal selected from the group consisting of Ru, Pt, and Rh; and    a p-channel MIS transistor including: an n-type semiconductor layer formed on the substrate; a pair of p-type source/drain regions formed in the n-type semiconductor layer and isolated from each other; a second gate insulating film formed on the n-type semiconductor layer and located between the pair of p-type source/drain regions; and a second gate electrode formed on the second gate insulating film and containing the selected metal.    
   
   
       10 . The semiconductor device according to  claim 9 , wherein: 
 the n-channel MIS transistor has a first tungsten layer provided between the first gate insulating film and the first gate electrode; and    the p-channel MIS transistor has a second tungsten layer provided between the second gate insulating film and the second gate electrode.    
   
   
       11 . The semiconductor device according to  claim 9 , wherein a ratio of the composition concentration (atomic %) of the rare-earth metal to the selected metal is in the range of 2.5 to 3.  
   
   
       12 . The semiconductor device according to  claim 9 , wherein a region in which a ratio of the composition concentration (atomic %) of the rare-earth metal to the selected metal is in the range of 2.5 to 3 is located at a portion of the first gate electrode on the side of the first gate insulating film, and has a film thickness of 1.5 nm or larger.  
   
   
       13 . The semiconductor device according to  claim 9 , wherein the rare-earth metal is one of Er, Y, La, Gd, and Yb.  
   
   
       14 . The semiconductor device according to  claim 9 , wherein the alloy of the selected metal and the rare-earth metal is RuEr 3  alloy.  
   
   
       15 . The semiconductor device according to  claim 9 , wherein an insulating film of the same material as the first gate insulating film is formed on side faces of the first gate electrode.  
   
   
       16 . The semiconductor device according to  claim 9 , wherein the second gate electrode has a stacked structure including a Ru layer, a buffer layer formed on the Ru layer and made of one of TiN, TaN, TaSiN, and TiSiN, and a polysilicon layer formed on the buffer layer.  
   
   
       17 . The semiconductor device according to  claim 16 , wherein the buffer layer is made of TiN.  
   
   
       18 . A method for manufacturing a semiconductor device, comprising: 
 forming a gate insulating film on a semiconductor layer;    forming a film containing a metal selected from the group consisting of Ru, Pt, and Rh, the film being provided on the gate insulating film;    forming a film containing a rare-earth metal on the film containing the selected metal; and    forming a gate electrode containing an alloy of the selected metal and the rare-earth metal by causing solid-phase reaction between the selected metal and the rare-earth metal through heat treatment.    
   
   
       19 . The method for manufacturing a semiconductor device according to  claim 18 , further comprising: 
 stacking a tungsten film on the film containing the selected metal after the film containing the selected metal is formed but before the film containing the rare-earth metal is formed;    forming a tungsten layer at an interface between the selected metal and the gate insulating film by diffusing tungsten through heat treatment; and    removing the remaining tungsten film from the film containing the selected metal.    
   
   
       20 . The method for manufacturing a semiconductor device according to  claim 18 , wherein the heat treatment is carried out at a temperature of 500° C. or lower.